January 2012 — The VLT in action

The VLT during observations. In this picture, the four 8.2-metre Unit Telescopes (UTs) are visible, named from left to right, Antu, Kueyen, Melipal and Yepun. In front of the UTs are the four 1.8-metre Auxiliary Telescopes (ATs), entirely dedicated to inter­ferometry. A reddish laser beam is being launched from UT4 (Yepun) to create an arti­ficial star at an altitude of 90 kilometres in the Earth's mesosphere. This laser guide star is part of the adaptive optics system, which allows astronomers to remove the effects of atmospheric turbulence, produc­ing images almost as sharp as if the tele­scope were in space.